title: A facile glovebox-free strategy to significantly accelerate the syntheses of well-defined polypeptides byN-carboxyanhydride (NCA) ring opening polymerizations.
abstract: A facile N2flow-acceleratedN-carboxyanhydride ring opening polymerization (NCA ROP) is demonstrated, herein, with rigorous kinetic studies to evaluate the methodology in detail. By usingn-hexylamine as initiator and γ-benzyl-L-glutamateN-carboxyanhydride (BLG-NCA) as monomer, the NCA ROPviaa normal amine mechanism (NAM) reached 90% conversion in 2 h under N2flow at room temperature in a fume hood, much shorter than the time required for the same polymerization conducted in a glove box (14 h). The efficient removal of CO2from the reaction by N2flow drove the carbamic acid-amine equilibrium toward the formation of active nucleophilic amino termini and promoted polymerization. The detailed kinetic studies of the polymerization with different feed ratios and N2flow rates were conducted, demonstrating the living feature of the NCA ROP and the tuning of the polymerization rate by simply changing the flow rate of N2. Maintenance of the reactivity of the amino ω-chain terminus and control during a subsequent polymerization were confirmed by performing chain extension reactions. The N2flow method provides a new straightforward strategy to synthesize well-defined polypeptides with predictable molecular weights and narrow molecular weight distributions (PDI < 1.19).
authors.affiliation: Department of Chemistry and Department of Chemical Engineering, Texas A&M University, P. O. Box 30012, 3255 TAMU, College Station, TX 77842 (USA).
authors.forename: Jiong
authors.initials: J
authors.lastname: Zou
authors.forename: Jingwei
authors.initials: J
authors.lastname: Fan
authors.forename: Xun
authors.initials: X
authors.lastname: He
authors.forename: Shiyi
authors.initials: S
authors.lastname: Zhang
authors.forename: Hai
authors.initials: H
authors.lastname: Wang
authors.forename: Karen L
authors.initials: KL
authors.lastname: Wooley
keywords: NCA; Nitrogen flow; ring opening polymerization